The invention relates to a coupling, in particular for machine tools driven by a motor, which is releasable when a predetermined triggering torque occurs, comprising a coupling element rotatable about an axis of rotation and having at least one first locking element, and an additional coupling element rotatable about the axis of rotation and having at least one second locking element, wherein in a coupled position the locking elements are aligned in a defined coupling rotary position relative to one another and in relation to the axis of rotation and are in an operative position engaging in one another and wherein in an uncoupled position the locking elements are disengaged in an inoperative position, and an elastic force storing means which acts on the locking elements in the coupled position in the sense of maintaining the coupled position.
Couplings of this type are known for machine tools driven by a motor. These serve primarily as safety couplings in order to prevent any further operation when the tool is blocked and thus any breaking of the tool or any release of the machine tool from its attachment.
Couplings of this type are preferably used in machine tools for driving drilling tools, in particular drill bits.
The known couplings are predominantly claw couplings, with which the locking elements designed as claws disengage at the occurrence of the countertorque in their momentary coupling rotary position but always engage again in additional, possible coupling rotary positions and must then be caused to disengage again by means of the triggering torque so that such known couplings "chatter". As a result, not only does a torque corresponding to the triggering torque occur at the first disconnection of the coupling but always subsequent to this additional torques of the order of magnitude of the triggering torque which act on the drive side of the coupling and, therefore, result in an increased wear and tear and/or increased attachment requirements not only with regard to the coupling but also on the drive side.
The object underlying the invention is therefore to improve a coupling of the generic type such that this no longer "chatters".